The subject matter disclosed herein relates to construction of rotating shafts. More specifically, the subject matter disclosed herein relates to high speed rotating shafts for, for example, engine power transfer.
Drive systems, such as those in rotor craft utilizing turbofan engines to drive the rotor craft rotors, utilize rotating drive shafts for power transfer. Combustion drives the turbofan turbine, which in turn drives rotation of the drive shaft, connected to the turbine. The drive shaft is connected to and drives a rotor assembly of the rotorcraft, in some instances, via a gearbox. Such shafts are typically formed from steel or other metallic materials, capable of rotation of about 7000-8000 rpm.
In some rotorcraft, however, it is required that the drive shaft rotate at high speed, up to about 10,000 rpm, due to rotational speeds of the turbofan engine used to increase operational efficiency of the turbofan engine. As such, a conventional steel shaft is not usable in such rotorcraft, as the steel shaft of required size and weight could not also meet the torque and bending stiffness requirements at such high rotational speeds, resulting in failure of the steel drive shaft, and or other components of the drive system and/or the rotor craft.